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SubjectRe: [Problem] System hang when I run pounder and syscall test on kernel 2.6.18-rc5
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Andrew Morton <akpm@osdl.org> wrote on 2006-09-08 10:14:34:

> On Thu, 7 Sep 2006 12:35:09 +0800
> Shu Qing Yang <yangshuq@cn.ibm.com> wrote:
>
> > Problem description:
> > I run pounder, scsi_debug on a machine. Then start 200 random
syscall
> > test
> > simultaneously. Tens of minutes later, the system hang.
>
> What is "pounder" and from where can it be obtained?
>
Thanks for your reply.

Pounder is part of ltp and locate in LTPROOT/testcases/pounder21.
It is a suit of test cases including mem_alloc, random_syscall, bonnie++,
etc.

> Running two tests at the same time complicates things. The next step
> should be to determine whether it is reproducible. If it is, then see
if
> it is reproducible with just one test running (presumably pounder?)
>
Running multiple cases simultaneously is to stress kernel more. And
because of
lack of machine resource I have no chance to reproduce it.

> It would be helpful to provide sufficient information to give others a
> chance of reproducing it: amount of memory, method for configuring the
> scsi-debug "disks", method for invoking pounder, etc.
>
The machine belongs to IBM p-Series with power5+ cpu and 2GB memory.
Run LTPROOT/testscript/ltp-scsi_debug.sh and
LTPROOT/testscript/pounder21/pounder directly.
No extra parameters. The command to load scsi_debug module is:
modprobe scsi_debug max_luns=2 num_tgts=2 add_host=2 dev_size_mb=20

> > Hardware Environment
> > Cpu type :power5+
> > Software Env:
> > kernel: 2.6.18-rc5
> > Base system: opensuse10
> >
> > Is the system (not just the application) hung?
> > Yes
> >
> > Did the system produce an OOPS message on the console?
> > No.
> >
> > Is the system sitting in a debugger right now?
> > Yes, xmon and sysrq are on.
> >
> > Additional information:
> > I use 'sysrq + t' then force system into xmon. And get following
> > message:
>
> Trace is a bit confusing. Ben (who is being shy) thinks it's this:
>
> > 0:mon> c1
> > 1:mon> e
> > cpu 0x1: Vector: 501 (Hardware Interrupt) at [c000000059f89ed0]
> > pc: c0000000000a4780: .release_pages+0xac/0x260
> > lr: c0000000000a5138: .__pagevec_release+0x28/0x48
> > sp: c000000059f8a150
> > msr: 8000000000009032
> > current = 0xc00000005f2b66b0
> > paca = 0xc0000000006b4500
> > pid = 16704, comm = shmctl01
> > 1:mon> t
> > [c000000059f8a280] c0000000000a5138 .__pagevec_release+0x28/0x48
> > [c000000059f8a310] c0000000000a7074 .shrink_inactive_list+0x944/0xa0c
> > [c000000059f8a580] c0000000000a7248 .shrink_zone+0x10c/0x168
> > [c000000059f8a620] c0000000000a7fe8 .try_to_free_pages+0x1c8/0x320
> > [c000000059f8a730] c0000000000a1954 .__alloc_pages+0x1ec/0x344
> > [c000000059f8a820] c00000000009de34 .find_or_create_page+0x8c/0x10c
> > [c000000059f8a8d0] c0000000000cba78 .__getblk+0x130/0x2d0
> > [c000000059f8a980] c0000000000ce1e0 .__bread+0x20/0x124
> > [c000000059f8aa10] c000000000166280 .ext3_get_branch+0xa4/0x158
> > [c000000059f8aac0] c000000000166620 .ext3_get_blocks_handle+0xf8/0xcf0
> > [c000000059f8aca0] c0000000001675cc .ext3_get_block+0x104/0x14c
> > [c000000059f8ad50] c0000000000cef64 .block_read_full_page+0x12c/0x390
> > [c000000059f8b220] c0000000000f81bc .do_mpage_readpage+0x5cc/0x63c
> > [c000000059f8b720] c0000000000f882c .mpage_readpages+0xf0/0x1b4
> > [c000000059f8b8c0] c000000000166450 .ext3_readpages+0x28/0x40
> > [c000000059f8b940] c0000000000a3c10
.__do_page_cache_readahead+0x194/0x2f0
> > [c000000059f8ba90] c00000000009e01c .filemap_nopage+0x168/0x460
> > [c000000059f8bb60] c0000000000ace18 .__handle_mm_fault+0x544/0xee4
> > [c000000059f8bc50] c00000000002db24 .do_page_fault+0x408/0x5e8
> > [c000000059f8be30] c0000000000048e0 .handle_page_fault+0x20/0x54
>
> Which indicates that a CPU is stuck in page reclaim.
>
> As a memory management/VM problem is suspected, a sysrq-M trace would be
> useful. That'll tell us whether the machine has exhausted physical
memory
> and/or swapspace.
>
I can not excute sysrq command now. But I can get memory allocation
information from xmon,
which indicates your guess may be right.

1:mon> mi
Mem-info:
DMA per-cpu:
cpu 0 hot: high 6, batch 1 used:5
cpu 0 cold: high 2, batch 1 used:1
cpu 1 hot: high 6, batch 1 used:5
cpu 1 cold: high 2, batch 1 used:1
cpu 2 hot: high 6, batch 1 used:5
cpu 2 cold: high 2, batch 1 used:1
cpu 3 hot: high 6, batch 1 used:3
cpu 3 cold: high 2, batch 1 used:1
cpu 4 hot: high 6, batch 1 used:5
cpu 4 cold: high 2, batch 1 used:1
cpu 5 hot: high 6, batch 1 used:4
cpu 5 cold: high 2, batch 1 used:0
DMA32 per-cpu: empty
Normal per-cpu: empty
HighMem per-cpu: empty
Free pages: 6976kB (0kB HighMem)
Active:6141 inactive:11012 dirty:4742 writeback:0 unstable:0 free:109
slab:11925 mapped:7 pagetables:7061
DMA free:6976kB min:5760kB low:7168kB high:8640kB active:393024kB
inactive:704768kB present:2097152kB pages_scanned:5172 all_unreclaimable?
no
lowmem_reserve[]: 0 0 0 0
DMA32 free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB
present:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
Normal free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB
present:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
HighMem free:0kB min:2048kB low:2048kB high:2048kB active:0kB inactive:0kB
present:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
DMA: 19*64kB 1*128kB 2*256kB 0*512kB 1*1024kB 0*2048kB 1*4096kB 0*8192kB
0*16384kB = 6976kB
DMA32: empty
Normal: empty
HighMem: empty
Swap cache: add 439156, delete 439156, find 50391/101032, race 26+79
Free swap = 0kB
Total swap = 855552kB
Free swap: 0kB
32768 pages of RAM
408 reserved pages
6834 pages shared
0 pages swap cached


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